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Comment by CodeGlitch | Hacker News Reader

Here's a good take on it:

https://news.sky.com/story/covid-news-latest-nhs-backlog-is-...

> Professor Andrew Hayward, of University College London, earlier told Sky News that it is unlikely there will be a variant more severe than Omicron.

He said: "This one will be hard to outcompete... given how successful it is."

Professor Hayward added that for a "variant to stick", it needs to have "some advantage over the existing variant and that advantage needs to be really in terms of increased transmissibility or escape from immunity".

He said: "There's no advantage to the virus itself becoming more severe."

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> He said: "There's no advantage to the virus itself becoming more severe."

I thought the virus doesn't care about becoming more or less sever since its transmission capability is all that matters to it and symptoms are hidden (thus increasing transmission between individuals) in the first days of infection and that's what evolution is driving him to be: more transmissible.

The fact symptoms appear sooner than delta seems to be a step backward for the virus in terms of efficacy and it's compensated by being way way way more virulent.

What am I getting wrong here ?

Also:

Omicron could as well have been more severe (and the jury is still out on long covid anyway). If there's another variant less virulent but compensated by hiding symptoms longer... then this would take over omicron and this variant could as well be more severe.

Is that totally out of the realm of possibilities ?

My regular joe thinking tells me that we can only be sure of the direction it's going to take when spring comes. 2021 had 5 vocs, it's only the first days of January.

Yes, I believe the high transmissibility before symptoms appear is the most beneficial trait to Omicron. However, if a variant appeared with exactly the same traits except that it was 10x more deadly, then a lot more people would be taking it more seriously, self-isolating and driving down infections. From an evolutionary perspective, there is an incentive for the virus to become milder rather than more deadly because of how the news of a deadly virus changes human behaviour.

But future human actions do not put evolutionary pressure on the virus. First the possible new variant emerges, our actions come later.

It's not like strains of the virus are made by intelligent design. The point is that Omicron became dominant because people due to a lot of factors, its high transmissibility and people's disinterest in quarantining among them. If Omicron 2.0 came out with the same transmissibility, but a notably higher lethality, people's interest in quarantining would have increased significantly, which could have prevented Omicron becoming the dominant strain in spite of its increased transmissibility.

Stats for symptom onset delay need to be disaggregated by vaccination status. Search text for "Kato" here:

https://thezvi.substack.com/p/omicron-post-12

I remember 6 months ago some researchers also said that Delta was so contagious that it is very unlikely that even more contagious variant arises. Oh well, sometimes unlikely events happen.

Based on what we see in other viruses, the practical evolutionary upper limit on R0 for respiratory viruses appears to be about 18.

https://www.vaccinestoday.eu/stories/what-is-r0/

Preliminary data on the Omicron variant indicates an R0 value in the 7 - 10 range. So SARS-CoV-2 might still have a little more room to evolve even higher contagiousness.

https://www.thelancet.com/journals/lanres/article/PIIS2213-2...

One thing that gives me pause here; at one time people were saying that _Delta_ would be very hard to outcompete, given how infectious it is.

Something as infectious as Omicron but with better immune escape would presumably do very well, even once the Omicron waves pass.

This doesn't make any sense, unless the variants directly compete against each other. But what we've seen with Omicron is that it can infect someone who just had Delta. So if there's a mutation that can infect someone that had Omicron, but is more severe that mutation can flourish, even if it is less transmissible than Omicron. It just flourishes in parallel.

They do directly compete, this s Is why delta is shrinking in these places.

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